Bojanic, R., and J. Roulier. “Approximation of Convex Functions by Convex Splines and Convexity Preserving Continuous Linear Operators”. Rev. Anal. Numér. Théorie Approximation 3, no. 2 (August 1, 1974): 143–150. Accessed November 23, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1974-vol3-no2-art3.